You can configure your NetScaler appliance to use direct server return (DSR) mode across Layer 3 networks by using IP tunneling, also called IP over IP configuration. As with standard load balancing configurations for DSR mode, this allows servers to respond to clients directly instead of using a return path through the NetScaler appliance, improving response times and throughput. As with standard DSR mode, the NetScaler appliance monitors the servers and performs health checks on the application ports.
With IP over IP configuration, the NetScaler appliance and the servers do not need to be on the same Layer 2 subnet. Instead, the NetScaler appliance encapsulates the packets before sending them to the destination server. After the destination server receives the packets, it decapsulates the packets, and then sends its responses directly to the client.
To configure IP over IP DSR mode on your NetScaler appliance, you must do the following: